The vast majority of sewing machines sold for residential use and indeed, for commercial use are of the fixed head and needle plate type. This is the traditional design and it is intended that the fabric work piece be moved by one means or another underneath the fixed head as opposed to moving the head relative to a fixed fabric work piece. In a typical sewing machine the needle head is aligned with the needle plate fixed to the base plate. The upper needle head is positioned at the distal end of an upper arm, which is interconnected to the lower arm which holds the base plate. This is often called the “throat” of the sewing machine and it is fixed in length; the longer the arms, the longer the throat of the sewing machine. A bobbin is located beneath the needle plate for the second portion of the thread to be fed through and there are usually a pair of feed dogs which are used to advance the fabric to be sewn underneath the needle. This conventional design is eminently practical and useful for the fabrication of items: clothing, as the fixed head and base plate assemblies are relatively small so that they can be inserted into a sleeve for a garment for example.
These fixed sewing machines can also be used to fabricate patch work quilts as they work well stitching in a straight line to sew together to pieces of quilt material. However, they do not work well when attempting to create a decorative quilt that has quilting stitching sewn in a decorative pattern, for example: displaying decorative outlines of horses running or rearing up on their hind legs.
A pantograph is generally defined as an instrument for copying and drawing a design on a different scale by a system of hinged or jointed rods. They have been known and used since the early 1600s. Generally there is one arm of the pantograph containing the small pointer while the other holds a drawing implement and by moving the pointer over a diagram, a copy of the diagram can be drawn on another piece of paper. By changing the positions in the arms in the linkage between the pointer and the drawing arm, the scale image produced can be changed from a direct 1:1 scale to a larger or smaller duplicate image. However, it is not a requirement that the pantograph be capable of adjusting the scale of the drawn image. In the sewing and quilting industry the term pantograph is commonly used simply replicating a design on a one to one scale.
These two technologies have been combined, for at least the past one hundred years to create an ability to replicate an embroidery design on a piece of fabric using a fixed head sewing machine. To achieve this goal, the drawing arm of the pantogram is not affixed to a right drawing instrument but rather is affixed to the fabric hoops in which the fabric work piece is secured. The fabric hoops move the work piece underneath the needle arm in direct relation to the movement of the pointer on the drawing and the pantogram arm is moved about by the operator. However, this only works for relatively small work pieces and is not readily adaptable for use with quilts which may be quite large, for example: ten feet long and six feet wide, and especially in cases where the embroidered design is to cover a major portion of the quilt with a decorative stitching of the desired design.
It is also possible to fix the quilt work piece to a fabric frame and stretch it underneath the fixed head work piece as long as the frame is connected to a movable carriage which moves in both the x and y direction, and may be computer-controlled. There are many prior art designs for quilting machines that incorporate this design. However, such a machine would require a lot of floor space and is not suitable for use in a residential home environment.
As a result, movable head sewing machines have been developed where the basic design can be described as having a stationary fabric frame, which is sometimes as long as fourteen feet from one end to the other, a sewing machine carriage which carries a fixed head and arm sewing machine that is movable in both the x and y direction, and typically employs handles, either at the rear or the front of the moveable head to control movement. It may also controlled by use of foot pedals to move the head relative to the stationary work piece which is stretched on the stationary frame. This design minimizes the floor space requirements for the machine, and quilting enthusiasts use these machines to create decorative quilts that are often times ten or twelve feet in length from one end to the other and several feet wide.
What is needed is some mechanism by which the moving head can be controlled with something like a pantograph so that a design can be traced from an image-bearing surface, such as a photograph, painting, or a line drawing, or even another embroidered product and the moving sewing machine head can be used to replicate whatever image is being replicated on the quilting fabric which is held in fixed relationship to the pantograph device.